We propose to use the center grant mechanism to bring together five exciting new methodologies and a rich longitudinal substance use data base, in order to develop innovative new methodologies, apply these methodologies to important substance use questions, and disseminate new methodologies to the field of prevention research. We propose to do this by establishing the Center for the Study of Prevention through Innovative Methodology at Pennsylvania State University. The Center will be made up of two cores and four distinct research projects. The four research projects are: a significant expansion of the latent Transition Analysis procedure to allow it to address a wider variety of prevention questions; a project to enhance survival and hazard models so that they have the capability to incorporate the multi-level structure so common in prevention data; a project to apply individual growth modeling to substance use data, and to expand this procedure and project to develop state-of-the-art missing data methods tailored to prevention issues and to make these methods easily accessible to researchers. Each of the four individual projects will apply the methodologies they develop and refine to important prevention research questions in a data set rich with information about substance use, a variety of risk factors, and other variables. All data originally collected as part of Project AAPT will be managed by the Scientific Core by use by all projects ina the proposed Center. The result will be a cohort-sequential data set including individuals ranging in age from ten to approximately 18. The four individual research projects will use these data to examine risk and protective factors across this important part of the lifespan.